1. Field of the Invention
The present invention relates to a method and apparatus for correcting the tilt of a light beam to optical recording mediums such as optical disks.
2. Description of the Related Art
In general, in recording and reproducing bits of information onto and from an optical disk, a tilt correcting technique has been adopted. The tilt correction is to correct a tilt of an optical beam (also known as “radial tilt”) to the information recording surface of an optical disk. Thus, when the tilt is corrected exactly, the optical beam should be radiated at right angles onto the information recording surface of an optical disk.
A conventional detection of the radial tilt has been carried out using a dedicated tilt sensor. Such a dedicated tilt sensor is configured to have an optical source to radiate a light beam dedicated for the radial tilt detection toward the information recording surface of an optical disk and a detector to receive reflected light from the optical disk for detection of an amount of the radial tilt.
One problem arising when using such a dedicated tilt sensor is that the sensor itself is larger in the physical size, thus making a pickup device equipped with the sensor larger in the size. Hence, a slim disk drive, which is often mounted in notebook-size personal computers, has faced this problem. That is, it is impossible for the slim disk drive to have such a tilt sensor mounted therein.